Hi Keith, it is really difficult to give you a good answer by just looking at a screenshot, can you please post the model file or send it to me at moi@moi3d.com?

My best guess from looking at the screenshot would be that possibly your straight section and your curved section may not be meeting each other in a completely tangent/smooth type way.

When surfaces like that meet at a very shallow creased angle, it tends to make things really difficult for the filleter to do some of the offset + intersection calculations. That may be why it is crunching away for a long time, but it is hard to say without being able to examine the model more closely.

It also may be difficult for the filleter to handle the corners along the sides of doing just that particular edge instead of the whole set of edges along that entire face.

You may also need to use a pretty small radius, there does not look like there is very much room there for the fillet to fit, try using something like 0.01 units and see if that works or not.

Another thing you can do if the edge filleter is unable to finish is to break your model apart into surfaces by using Edit/Separate and then create fillets by selecting 2 surfaces at a time and running Fillet - that will do a surface/surface fillet calculation instead of an edge-based one, it will tend to work to create a fillet surface where the edge one got confused due to difficulty in processing corner junctures. However, you will have to then trim and fill in corners yourself with that method.

- Michael